The word bimetallistic refers to a monetary system based on the use of two metals, usually gold and silver. If you're writing about this topic, it's helpful to have some synonyms in your arsenal to avoid repetition and improve the flow of your writing. Some possible alternatives for bimetallistic include dual-metallic, binominal, two-fold, or double-standard. Another option is to use phrases such as "a mixed metallic standard" or "a system of bi-metallic currency." Whatever phrasing you choose, the key is to convey the idea of a monetary system that relies on two different metals rather than just one.